Plate mill and process of rolling hot metal



Oct. 16, 1928. 1,688,252

J. B. TYTUS PLATE MILL AND PROCESS OF ROLLING HOT METAL I Filed April11, 1925 ATTO/P/VfVS.

Patented Oct. 16,1928.

UNITED STATES PATENT OFFICE.

JOHIV B. TYTUS, OF MIDDLETOWN, OHIO, ASSIGNOR TO THE AMERICAN ROLLINGMILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORATION OF OHIO.

PLATE MILL AND PROCESS OF ROLLING HOT METAL.

Application filed April 11, 1925. Serial No 22,272.

My invention relates to processes for roll ing hot metal andparticularly to continuous processes, wherein the metal piece is movedfrom onestand of rolls to another without being given more than one passin each stand.

It has been proposed in the past in providing for the rolling of hotmetal, in order to get a rapid reduction, to utilize a four high standof rolls in which the two inner rolls were of small diameter therebygiving a maximum reduction in each pass, while the outer rolls bybacking up the two inner rolls serve to reinforce them against excessivespringing.

I have found, however, that it is not necessary to utilize a four highstand of rolls, and that by the use of an ordinary two high stand, inwhich means is provided to support a smaller diameter idle roll betweenthe two main rolls, I am enabled to get a quick reduction and at thesame time have a mill which is readily convertible to a two high mill,by removing the small diameter roll.

I have also found that where several mills of the three high type, usina small diameter idle roll for engaging the piece on one side, arearranged in tandem or so as to operate as a continuous mill, that thefit of the piece when rolling plate for example must be provided for inthe several stands.

Thus the stands following the first stand must be so arran ed as to havean active pass which properly ts the shape to which it has been forcedby the stand preceding it.

In other words, the first stand due to its central spring, will presentan openin through which the metal is forced whic gives it a slightconvexity. The second stand must be arranged so that its convexity ofopening will be such as to fit as closely as possible the shape of themetal from the first stand, and so on through the succeeding stands in atandem or continuous train.

One solution of this provision for fit of the piece in successive standsof the type noted, which I have discovered, is to form the rolls of thefirst stand, and particularly the small diameter roll, in such a waythat a comparatively large convexity of openin between the rolls will bepresented to the piece. The next stand I arrange to present a convexityof opening somewhat less, and the third stand still less, and so on, thenumber of stands being limited by the length of the piece which it ispractical to handle.

It should be understood that in the rolling mill there are a number offeatures attendant upon the shape of opening of the rolls, and that thedesigner and operator will have to take these features intoconsideration in providing for the graduated con.- vexity of activepass.

It is mfy object, as stated, to provide for rolling 0 hot metal,particularly in plate mills, by means of successive reductions on thepiece, each reduction to take place in a different stand, and to arrangefor rapid reduction of the piece by providing a small diameter for oneof the rolls that engages the piece.

This object I provide by that certain process of rolling, andarrangement of rolling mills to be hereinafter more specifically pointedout and claimed.

In the drawing Figure 1 is a partially diagrammatic view of three standsof rolls arranged in tandem. Figure 2 is a diagram of the progressiveactive passes of several roll stands.

It should'be understood that in a tandem train of rolls, the pieceemerges from the active pass of one stand before it enters the activepass of the next, and that in a continuous train, the piece isengaged bymore than one stand at the same time. The latter requires a differentialspeeding of the several stands, and the former a differential spacin soas to accommodate the increasing lengt of the piece as it emerges fromeach stand. I find it simpler to arrange the mill for my process as atandem, although I do not wish to exclude continuous trains.

In the drawing, the first stand of rolls shows a lower driven roll 1,and central idle roll 2 of relatively small diameter, and a backin roll3, like the first roll, although it may fie of different size, ifdesired. The roll 3 imparts stiifness against bending to the roll 2, andthe screw 4 is employed to re ulate the movement of this upper roll, theower-roll being preferably fixed in its journals, and the rolls 2 and 3being permitted upward movement away from the roll 1, as controlled bythe screw. This form of screw control is accepted practice, in rollingmills, and needs no particular illustration.

The feed tables between the stands of rolls are indicated at 5 and 6,and the second stand of rolls shows bottom roll 1*, central roll 2*, andtop roll 3 while the third stand shows bottom roll 1*, central roll 2and top roll 3. In the illustration all stands are alike to each other,and due to the differential spacing may be used as a tandem train, eachbeing driven at'the same speed.

The convexities referred to as being arranged in the active pass of thestands of rolls, are so slight to the eye that it is not practical toillustrate them on a small scale drawing, but it Will be understood thatroll 2 will have a selected concavity, dependent upon roll spring, rollshape, roll temperature, temperature and kind of piece delivered, andshape and thickness of the piece. The second stand will have a lesserconvexity of active pass than the first, and the second will have morethan the third. The turning of the rolls preliminary to a rollingoperation is thus only one of the factors of the resulting active passof the rolls, and the operator must control the active pass, workingwith the instrumentalities involved. Thus in Figure 2 are shown threeactive passes, A, B and C, the series showing progressively lessconvexity.

The mill shown is used in rapid reduction, of relatively thin plates orpacks, in which the pressure factor and resilience of housing result inthe ordinary diameter rolls being ineffective in processes of reductionby individual pass through successive stands.

As the piece enters each stand, it passes between the lower roll and thecentral roll, thus being positive-1y fed by the lower roll,

and grasped between it and the central roll which has a small diameterand thus effects a rapid reduction of the piece.

Were a four high stand to be used with two idler rolls of smalldiameter, in a continuous or tandem train, not only would the mill bemore cumbersome and costly of upkeep, but it would not be convertible toa two high stand to suit special conditions, nor would it result in thepiece passing over a roll which is positively driven. Then again theactive pass of a stand where two small diameter rolls are used, with thepiece passing between the small rolls, as has been proposed in the past,cannot be controlled as readily as in the three high arrangement which Ihave described.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is

1. A process of rolling hot metal which consists in passing the metalthrough successive stands of rolls arranged in line, and in selectedstands engaging the metal with a roll of a small diameter to givemaximum reduction and a large roll opposed to the small one andpositively. driving the large roll, and arranging the active passof'each stand to enforce progressively less convexity on the piece.

2. A plate mill of the character described, comprising a plurality ofstands of rolls, each having a driven, lower, large diameter roll, acentral, small diameter idler roll, and a top larger diameter, and screwcontrolled roll, said stands arranged to act successively on the piece,said rolls being so constructed and operated as to present progressivelyless con vexity of opening, through which the piece must pass, from thefirst to the last stand.

JOHN B. TYTUS.

